Children's Ideas About Solids, Liquids, and Gases

Below are common ideas children in grades K-6 have about
this topic, compiled from research on children's ideas about science. Consider
what evidence might refute this idea, and why a child would be likely to
believe this? Once you've entered all your answers you can click "printable
page" at the bottom of this form to print your answers. You can also
click "see possible response" for any question to see one possible
response from the
series content advisors.

1. Matter is continuous and static.

Children’s everyday experience does not
include the microscopic world of particles, and solids/liquids
do not appear to move when at rest. However, many macroscopic
behaviors, like the fact that gases can be compressed or that solids
expand when heated, would not be possible if matter were continuous.
In the former case, the amount, or mass, of gas would have to decrease
(impossible, because matter can never be created or destroyed)
and, in the latter case, the solid would have to gain mass (again,
impossible). The evidence that matter is not static can be seen
in the Brownian Motion of particles that can be observed under
a microscope, as demonstrated in the video with a mixture of oil
and water. Hide
Response

2. Most gases contain air and are weightless, invisible, and/or are poisonous.

Children are often confused about the nature of gases, because
many gases they encounter in everyday are invisible — like
air — and are very light. They may have also had experience
with a gas stove or heater, which are dangerous when unlit, or
heard about poisonous gases from the media. However, what we call
air is actually a mixture of gases, e.g. nitrogen, oxygen, and
carbon dioxide, all of which have weight. Many gases, like helium
and hydrogen, are pure, i.e., contain no air or other gases, and
some like iodine have color. Many gases aren’t poisonous
and, perhaps most importantly, any substance can change state to
a gas if its liquid form is heated to its boiling point. Hide
Response

3. Particles of a solid have all or most of the bulk solid’s
properties, including hardness, hotness/coldness, color, and
physical state.

Most children don’t have a grasp of the difference in scale
between the macroscopic world and the microscopic world. All material
can exist in any state, so hardness and other properties are only
characteristics of one state, not of the particles that make it
up.Hide
Response